Toxic slime sickened hundreds of people and animals in a two-year period, CDC says
Exposure to toxic algae sickened hundreds of people and animals across the country during a two-year period in which researchers examined the health effects of the growing environmental threat that has recently afflicted lakes in South Carolina.
The U.S. Centers for Disease Control and Prevention, in a new study released this week, found that 389 people and 413 animals had become ill after encountering harmful algae in lakes, rivers, the ocean and other water bodies from 2016-2018.
The study is only a snapshot of the health problems caused by harmful algae, since only 18 states provided data. But the CDC is seeking to gather information from states that did not provide data — including South Carolina — to give a more detailed picture in future reports. In the Southeast, North Carolina, Florida and Virginia were among states participating in the study.
“South Carolina may not be participating right now, but I can promise you, this is not skipping over that state,’’ CDC spokesman Brian Katzowitz said, noting that harmful algae outbreaks “are fairly widespread’’ nationally.
Many scientists suspect rising global temperatures, along with fertilizer runoff from large farms and from lawns in high-growth areas, are improving conditions for toxic algae blooms. Harmful algae blooms are most prevalent in the summer but increasingly of concern earlier in the spring and later in the fall.
Even though South Carolina data were not included in the study, the state has had recent issues with algae outbreaks.
The S.C. Department of Health and Environmental Control put out multiple statements and advisories in 2020 about harmful algae blooms. The state identified outbreaks at small lakes in Barnwell, Cherokee and Lancaster counties, as well as at Lake Wateree, a major recreational lake in Fairfield County north of Columbia. Lake Wateree also had an outbreak of toxic algae in 2019 that drew the attention of scientists.
Virginia Roberts, the lead researcher on the CDC’s recent report, said the health threats to people, pets and wildlife should not be ignored.
“There’s a concern that, as waters are warming or there other kind of environmental changes that support the growth or the longevity of blooms .... this could make them more severe and it could increase the potential for people or animals to be exposed,’’ Roberts said in an interview with The State. “We’ll certainly be on the lookout for that sort of thing.’’
The CDC study said that of the 389 people sickened by harmful algae nationally, most experienced gastrointestinal ailments, or upset stomachs. Others suffered headaches and fever, skin discomfort, and ear, nose and throat problems, the study said. One algae outbreak at a lake in Utah was among the largest single blooms that caused health problems in people, the CDC said.
None of the people sickened by toxic algae nationally died, but it was a different story for animals, particularly wildlife.
About 300 birds died from a toxic algae outbreak at a lake in 2018, according to the study, which did not identify the state or lake where the deaths occurred.
Dogs and cattle were among the domestic animals more commonly killed or sickened by toxic algae outbreaks, the study said. In 2019, dogs died in North Carolina and Georgia after coming in contact with toxic algae, McClatchy has reported.
Dogs may be vulnerable to serious health issues from toxic algae when they venture into lakes or rivers, unaware of the threats. Canines are smaller than most people and act differently in water where harmful algae concentrate, Roberts said.
“Imagine if you bring a dog to a lake,’’ Roberts said. “It runs through the water. It splashes around, it comes out and licks its fur. It might eat something off the ground.’’
Dogs “might end up taking in more toxin,’’ she said.
The CDC study found about 90% of the harmful algae outbreaks in the 18 states occurred in lakes, rivers, streams and other freshwater bodies that draw people and their pets, particularly during warm weather months.
While algae blooms often gain attention at ocean beaches, University of South Carolina researcher Geoff Scott said the study’s finding is not surprising. Previous research has shown a majority of harmful algae blooms occur in freshwater, he said. Scott was not a part of the study but directs a center at USC that is examining algae in lakes.
Freshwater algae blooms are not new, “but the frequency and geographic distribution’’ of a group of freshwater algae — cyanobacteria — seems to have “dramatically increased in recent decades in the United States and globally,’’ according to a government interagency working group study of freshwater algae.
The human health effects of freshwater algae blooms are a concern, but algae also can affect the taste and quality of drinking water. That’s a possible reason water drawn from Lake Murray had an earthy taste last year, The State has reported.
A spokeswoman with the S.C. Department of Health and Environmental Control said Friday the agency was not asked to participate in the CDC’s study, but is willing to collaborate in the future.
DHEC did not have statistics available to show the number of people in South Carolina whose health has been affected by toxic algae since 2016. The agency would not speculate on whether more people might be sickened by toxic algae in the future, spokeswoman Laura Renwick said.
This story was originally published December 19, 2020 at 12:46 PM.
